Self-interaction correction for band structure calculation based on local density approximation of iron nitrides

The band theory based on the conventional local density approximation (LDA) has not given a quantitative explanation of the mechanism of the giant magnetization of alpha ''-Fe16N2 thin film. In this paper, the self-interaction correction (SIG) is applied to the LDA band calculation of alpha ''-Fe16N2. The electronic structure is calculated by the self-consistent linearized augmented plane wave (LAPW) method. It can be concluded that the influence of the SIC for alpha ''-Fe16N2 is large, although the calculated electronic structures of 3d transition metals and gamma'-Fe4N are little affected by the SIG. The charge density distribution of alpha ''-Fe16N2 is uniformly broadened. It appears that the distribution for some sites of Fe atoms in alpha ''-Fe16N2 is different from that of bcc Fe atoms. However, the SIC has little effect on the total magnetic moment. The SIC is unable to explain the giant magnetic moment. It seems that the orbits of iron nitride are probably metallic bond-like, whose orbit is Bloch function-like, although the localization of some sites of Fe atoms of alpha ''-Fe16N2 results in more influence than that of gamma'-Fe4N.